Just-in-time feedback device

As seen on an Air-France counter, a tactile device to get people's feedback. What is interesting here:

On the HCI side: The absence of screen on the device, what is important for the company is only the answers, nothing is really needed to be shown to the person who is pressing the buttons. It's a one-way interface.

On the context side: real-time feedback that can be gained with devices like this, in context. It of course leads to wonder about the best moment to ask people's feedback when traveling: when the interaction occur OR after a while when people had some time to filter out the plus and minuses of their experience. But wait, is life only about +/-?